When observing constructions of the skin, conditions of the hair, etc., hand-held microscopes have been frequently used in the fields of medicine, cosmetics, etc. recently, as well as applications of such microscopes have been under development in the field of the manufacturing industry for various machines, and electric and electronic products, or machines, electronic and electric parts to be used therewith.
Among them, when illustrating an example in the case of an ultra-small package BGA soldering, the BGA of this type has come to be more and more frequently used in a wide variety of utilities, such as LSI's in mobile phones, digital camera built-is VTR's, high-performance microprocessors in mobile information terminals. Now, in attaching the BGA to the board, soldering balls of the BGA are soldered onto the board under a predetermined temperature, and in order to achieve the optimal attachment, it is necessary to determine the appropriate temperature by examining the soldering conditions.
However, as means for observing and examining how adequately the soldering balls of the BGA are reliably attached to the board, there are the examinations by electricity transmission and X-ray transmission; nonetheless, the reality is that the associated therewith cost turns out to be extremely high.
At the same time, the soldering balls of the BGA are extremely microscopic as their diameter ranges somewhere between hundreds of microns and one millimeter, the conventional visual observation means, for example, the means using a mirror, etc., cannot fully reveal the soldering conditions.
FIG. 24 is a schematic diagram, showing a conventional example in observing the soldering conditions; where (a) is an observation example by a mirror whereas (b) is an observation example by a prism. It shall be noted that the arrows in the diagrams signify illuminating light.
As shown in FIG. 24(a), by the conventional examination using the mirror 1, when observing the soldering conditions of the soldering ball 4 of the BGA 3 soldered onto the board 2, the conventional mirror 1 makes it hard to observe the bottom part, where the soldering ball is attached to the board 2 because of the thickness 5 of the mirror; moreover, the depth 6 of the mirror is huge, so the usage in extremely narrow portions is difficult.
Likewise as shown in FIG. 24(b), the conventional examination using a prism 7, the bottom of the part, where the soldering ball 4 is attached to the board 2 can be observed; however, the dimension 8 of the prism itself is formed so that its width becomes rather wide, so the usage in extremely narrow portions is difficult.
Furthermore, with the conventional microscope, when visually observing, for example, the human skin, or the hairline, regions that come in sight are small, and clear images are hard to obtain, which has left a room for further improvements.
Given the situation, one of the objectives of the present invention is to provide a wider horizon, which makes it possible to make a horizontal observation in an extremely narrow space, and can be manufacturerd at a less expensive price.
Moreover, another objective of the present invention is to provide a charge-coupled device-type video microscope that is suitable for a video observation by incorporating a lighting device into the body of such a microscope in order to irradiate illuminating light efficiently, and preferably by incorporating a charge-coupled device camera.